Please read the links:
Avidya and Ahankara(Ignorance and Egoism)
Maya and Avidya
Here Swami Sivananda explains avidya and its relation to ahankara and maya. Moreover, Sri Ramanuja talks about "vishishtadvaitham" which means "a special case of Advaitham" which is also about a special case of non-duality!
Bhagavad Gita 4.22
yadṛcchā—out of its own accord; lābha—gain; santuṣṭaḥ—satisfied;
dvandva—duality; atītaḥ—surpassed;vimatsaraḥ—free from envy;
samaḥ—steady; siddhau—in success; asiddhau—failure; ca—also;
kṛtvā—doing; api—although; na—never; nibadhyate—is affected.
He who is satisfied with gain which comes of its own accord, who is free from duality and does not envy, who is steady both in success and failure, is never entangled, although performing actions.
With warm Regards